subtlecrypto: Don't throw exceptions twice when converting to Algorithm object (#34239)

* Don't throw exceptions twice when converting to Algorithm object

Removes match statements like
```rust
let Ok(ConversionResult::Success(algorithm)) = Algorithm::new(cx, value.handle())
else {
    return Err(Error::Syntax);
};
```
These don't cause issues if `Algorithm::new` returns `Ok(ConversionResult::Failure`,
but in the case of `Err(())` the implementation already called `throw_type_error`
and we must not throw an additional Syntax error, otherwise we'll crash.

Luckily, this case is already handled elsewhere by the
`value_from_js_object` macro.

Signed-off-by: Simon Wülker <simon.wuelker@arcor.de>

* Test that calling subtlecrypto methods with empty algorithm objects throws a TypeError

The WebCryptoAPI spec does not tell us which error to throw exactly, but
according to https://webidl.spec.whatwg.org/ it should be a TypeError.

This previously crashed servo.

Signed-off-by: Simon Wülker <simon.wuelker@arcor.de>

---------

Signed-off-by: Simon Wülker <simon.wuelker@arcor.de>

tests/wpt/meta/MANIFEST.json

@@ -358512,7 +358512,7 @@
     },
     "generateKey": {
      "failures.js": [
-      "e0f0279a69bb885eb30cbe086796c281db0245bb",
+      "deaac636a99be570b118d8e8f8096b36a4a0b28f",
       []
      ],
      "successes.js": [
@@ -358526,7 +358526,7 @@
       []
      ],
      "importKey_failures.js": [
-      "bba48401e616a564200570dddb2fe06d762347fe",
+      "077ae076c648b097977cdbc484eaf79db884f7b2",
       []
      ],
      "okp_importKey.js": [
@@ -516888,7 +516888,7 @@
     },
     "digest": {
      "digest.https.any.js": [
-      "379d9311f30247b85e2e5ea8981d1d180fe783a1",
+      "3b0972b1f2bf7d5a285765ab7cf2447acca21467",
       [
        "WebCryptoAPI/digest/digest.https.any.html",
        {